Environmental Fate and Transport Modeling for Perfluorooctanoic Acid Emitted from the Washington Works Facility in West Virginia

Abstract

Perfluorooctanoic acid (PFOA) has been detected in environmental samples in Ohio and West Virginia near the Washington Works Plant in Parkersburg, West Virginia. This paper describes retrospective fate and transport modeling of PFOA concentrations in local air, surface water, groundwater, and six municipal water systems based on estimates of historic emission rates from the facility, physicochemical properties of PFOA, and local geologic and meteorological data beginning in 1951. We linked several environmental fate and transport modeling systems to model PFOA air dispersion, transit through the vadose zone, surface water transport, and groundwater flow and transport. These include AERMOD, PRZM-3, BreZo, MODFLOW, and MT3DMS. Several thousand PFOA measurements in municipal well water have been collected in this region since 1998. Our linked modeling system performs better than expected, predicting water concentrations within a factor of 2.1 of the average observed water concentration for each of the six municipal water districts after adjusting the organic carbon partition coefficient to fit the observed data. After model calibration, the Spearman's rank correlation coefficient for predicted versus observed water concentrations is 0.87. These models may be useful for estimating past and future public well water PFOA concentrations in this region.

Equilibrium modeling: A pathway to understanding observed perfluorocarboxylic and perfluorosulfonic acid behavior

“…It has been suggested, but neither tested nor proven, that the standard equilibrium models for neutral organics are not applicable to the chemicals in the present study because of their ionization, the small fraction of neutral species present at environmentally relevant pHs, the surface active and amphiphilic nature of PFCs, and the formation of a tertiary layer in air-water systems [2][3][4][6][7][8]. Much effort has therefore already been devoted to developing new and fundamentally different models [1,5,17] and explanations for observed concentrations [4] specific and applicable to only these fluorinated chemicals by virtue of their perceived uniqueness. This perceived uniqueness is caused, at least in part, by the historical convention of using the name of the parent acid for all properties of either the neutral species or the ionic conjugate base, thus obscuring the identity of the species to which the property pertains.…”

“…It has been hypothesized that the standard equilibrium models typically used for neutral organic chemicals are not applicable to perfluorocarboxylic acids (PFCAs) and their carboxylates (PFCs), herein collectively referred to as PFC(A)s, and not applicable to perfluorosulfonic acids (PFSAs) and their sulfonate ions (PFSs), herein collectively referred to as PFS(A)s [1][2][3][4][5][6][7][8]. To gain an understanding of what is needed to develop models that are applicable to this set of chemicals, the present study seeks to disprove the counter hypothesis i.e., that the standard models are applicable to PFC(A)s and PFS(A)s. A detailed understanding of specifically where and how the models fail has been absent from the literature and remains conjecture.…”

Shifts in production of perfluoroalkyl acids affect emissions and concentrations in the environment of the Xiaoqing River Basin, China

“…At another fluoropolymer facility owned by DuPont located in West Virginia, concentrations of PFOA as great as 78 g/L have been observed in groundwater [5]. This has brought high concerns for health of local residents and they have been supplied with alternative sources of water [22]. Although recent studies implied that PFOA is becoming the dominant PFAA in surface waters, such as Taihu Lake, China (max.…”

Behavior and Fate of PFOA and PFOS in Sandy Aquifer Sediment

“…A recent effort to model concentrations of PFOA and PFOS in municipal water supply wells ignored the contribution of mineral surfaces, and modeled sorption solely as a function of the content of organic matter (Shin et al 2011). To fit their model to existing field data, it was necessary to assume a log K oc for PFOA of 0.4 (L/kg).…”

“…At a site in Cottage Grove, MN, concentrations of PFOA and PFOS in ground water have been as high as 120 and 105 µg/L respectively (Rumsby et al 2009). Concentrations of PFOA in two municipal water supply wells near the Little Hocking site in West Virginia have exceeded 10 µg/L (Shin et al 2011). The maximum concentration was 24 µg/L.…”